Analysis of a human gene homologous to rat ventral prostate.1 protein

Expression of Claudin-9 (CLDN9) in Breast Cancer, the Clinical Significance in Connection with Its Subcoat Anchorage Proteins ZO-1 and ZO-3 and Impact on Drug Resistance

(1) Introduction: Claudin-9 (CLDN9) is a member of the claudin protein family, a critical transmembrane protein family for tight junctions that are implemented in the progression of numerous cancer types. The present study investigated the role that CLDN9, along with the subcoat proteins, Zonula Occludens (ZOs), plays in clinical breast cancer and subsequent impact on drug response of patients. (2) Methods: CLDN9 protein and CLDN9 transcript were determined and correlated with clinical and pathological indicators, together with the status of hormonal receptors. The levels of CLDN9 transcript were also assessed against the therapeutic responses of the patients to chemotherapies by using a dataset from the TCGA database. Breast cancer cell models, representing different molecular subtypes of breast cancer, with differential expression of CLDN9 were created and used to assess the biological impact and response to chemotherapeutic drugs. (3) Results: Breast cancer tissues expressed significantly higher levels of the CLDN9, with the high levels being associated with shorter survival. CLDN9 was significantly correlated with its anchorage proteins ZO-1 and ZO-3. Integrated expression of CLDN9, ZO-1 and ZO-3 formed a signature that was significantly linked to overall survival (OS) (p = 0.013) and relapse-free survival (RFS) (p = 0.024) in an independent matter. CLDN9 transcript was significantly higher in patients who were resistant to chemotherapies (p < 0.000001). CLDN9 connection to chemoresistance was particularly prominent in patients of ER-positive (ER(+)), Her-2-negative((Her-2(-)), ER(+)/Her-2(-) and triple-negative breast cancers (TNBCs), but not in patients with HER-2-positive tumors. In Her-2-negative MCF7 and MDA-MB-231 cancer cells, loss of CLDN9 significantly increased sensitivity to several chemotherapeutic drugs including paclitaxel, gemcitabine and methotrexate, which was not seen in Her-2(+) SKBR3 cells. However, suppressing Her-2 using neratinib, a permanent Her-2 inhibitor, sensitized cellular response to these chemodrugs in cells with CLDN9 knockdown. (4) Conclusions: CLDN9 is an important prognostic indicator for patients with breast cancer and also a pivotal factor in assessing patient responses to chemotherapies. Her-2 is a negating factor for the treatment response prediction value by CLDN9 and negating Her-2 and CLDN9 may enhance breast cancer cellular response to chemotherapeutic drugs.

Phytochemicals and inflammatory bowel disease: a review

Gastrointestinal tract is the second largest organ in the body that mainly functions in nutrients and minerals intake through the intestinal barrier. Intestinal permeability maintains the circulation of minerals and nutrients from digested foods. Life and all the metabolic processes depend either directly or indirectly on proper functioning of GI tract. Compromised intestinal permeability and related disorders are common among all the patients with inflammatory bowel disease (IBD), which is a collective term of inflammatory diseases including Crohn's disease and ulcerative colitis. Many synthetic drugs are currently in use to treat IBD such as 5-aminosalicylic acid corticosteroids. However, they all have some drawbacks as long-term use result in many complications. These problems encourage us to look out for alternative medicine. Numerous in vitro and in vivo experiments showed that the plant-derived secondary metabolites including phenolic compounds, glucosinolates, alkaloids, terpenoids, oligosaccharides, and quinones could reduce permeability, ameliorate-related dysfunctions with promising results. In addition, many of them could modulate enzymatic activity, suppress the inflammatory transcriptional factors, ease oxidative stress, and reduce pro-inflammatory cytokines secretion. In this review, we summarized the phytochemicals, which were proven potent in treating increased intestinal permeability and related complication along with their mechanism of action.

Claudin-7 suppresses the cytotoxicity of TRAIL-expressing mesenchymal stem cells in H460 human non-small cell lung cancer cells

Evidence suggests that the cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising candidate for cancer therapeutics. Studies have also shown that claudin-7 (CLDN7) expression is variably dysregulated in various malignant neoplasms, with a role in lung cancer that has not been definitively decided. This work investigated the differential sensitivity of CLDN7-overexpressing human NSCLC H460 cells to TRAIL in vitro and in mouse xenografts, and explored the molecular mechanisms responsible for these effects. NCI-H460 cells were transfected or not with green fluorescent protein-tagged CLDN7. Each group was then exposed to mesenchymal stem cells (MSCs) or red fluorescent protein-tagged MSCs transduced with lentivirus expressing membrane-bound TRAIL. The effects and related mechanisms of these treatments were evaluated in vitro, and in vivo in murine xenografts. Our results indicate that TRAIL induced apoptosis in H460 cells in vitro, and in established xenograft tumors TRAIL was associated with a decrease in tumor size, tumor weight, and circulating tumor cells. CLDN7 was found to inhibit the MEK/ERK signaling pathway, leading to inhibition of death receptor 5 (TNFRSF10B). The cytotoxicity of TRAIL was confirmed in H460 cells and in vivo, and CLDN7 suppressed the cytotoxicity of TRAIL in H460 cells. Our results indicate that TRAIL may be a useful therapy to enhance apoptosis in CLDN7-negative lung cancer cells.

Transcriptional activities of histone H3, cyclin D1 and claudin 7 encoding genes in laryngeal cancer

Uncontrolled proliferation and a decrease in cell-cell adhesion are one of the most important characteristics of malignancy. Determination of replication-dependent histone H3 can be applied as a proliferative marker. Cyclin D1 (CCND1) regulates the cell cycle by participating in the control of the G1/S phase transition. Claudins (CLDN) are components of tight junctions and may play an essential role in the loss of tissue cohesion. The aim of the study was to assess the mRNA expression of histone H3, cyclin D1, and claudin 7 genes in laryngeal squamous cell carcinoma (LSCC) and adjacent nonneoplastic tissues. The study group consisted of 32 patients with LSCC. Adjacent nonneoplastic tissues of incision lines were used as controls. Quantification of H3, CCND1 and CLDN7 mRNAs was performed by the use of real-time QRT-PCR assay. Molecular analysis showed a significantly higher expression of CCND1 (P = 0.0001; Wilcoxon test) and H3 (P = 0.0141) genes in tumor tissues than in surrounding nonneoplastic tissues. On the contrary, transcriptional activity of claudin 7 gene was higher in histologically normal tissues; however, this difference was not statistically significant (P = 0.1499). The data obtained indicate that laryngeal cancer is characterized by high proliferative potential mediated by increase in cyclin D1 and H3 mRNAs expression.

Dysregulation of claudin-7 leads to loss of E-cadherin expression and the increased invasion of esophageal squamous cell carcinoma cells

The claudins constitute a 24-member family of proteins that are critical for the function and formation of tight junctions. Here, we examine the expression of claudin-7 in squamous cell carcinoma (SCC) of the esophagus and its possible role in tumor progression. In the normal esophagus, expression of claudin-7 was confined to the cell membrane of differentiated keratinocytes. However, in the tumor samples, claudin-7 expression is often lost or localized to the cytoplasm. Assaying esophageal SCC lines revealed variable expression of claudin-7, with some lacking expression completely. Knockdown of claudin-7 in SCC cell lines using a small interfering RNA approach led to decreased E-cadherin expression, increased cell growth, and enhanced invasion into a three-dimensional matrix. The opposite was observed when claudin-7 was overexpressed in esophageal SCC cells lacking both claudin-7 and E-cadherin. In this context, the claudin-7-overexpressing cells became more adhesive and less invasive associated with increased E-cadherin expression. In summary, we demonstrate that claudin-7 is mislocalized during the malignant transformation of esophageal keratinocytes. We also demonstrate a critical role for claudin-7 expression in the regulation of E-cadherin in these cells, suggesting this may be one mechanism for the loss of epithelial architecture and invasion observed in esophageal SCC.

Barriers built on claudins

The fundamental functions of epithelia and endothelia in multicellular organisms are to separate compositionally distinct compartments and regulate the exchange of small solutes and other substances between them. Tight junctions (TJs) between adjacent cells constitute the barrier to the passage of ions and molecules through the paracellular pathway and function as a 'fence' within the plasma membrane to create and maintain apical and basolateral membrane domains. How TJs achieve this is only beginning to be understood. Recently identified components of TJs include the claudins, a family of four-transmembrane-span proteins that are prime candidates for molecules that function in TJ permeability. Their identification and characterization have provided new insight into the diversity of different TJs and heterogeneity of barrier functions in different epithelia and endothelia.

Williams-Beuren syndrome: a challenge for genotype-phenotype correlations

Many human chromosomal abnormality syndromes include specific cognitive and behavioural components. Children with Prader-Willi syndrome lack a paternally derived copy of the proximal long arm of chromosome 15, and eat uncontrollably; in Angelman syndrome lack of a maternal contribution of 15q11-q13 results in absence of speech, frequent smiling and episodes of paroxysmal laughter; deletions on 22q11 can be associated with obsessive behaviour and schizophrenia. The neurodevelopmental disorder Williams-Beuren syndrome (WBS), is caused by a microdeletion at 7q11.23 and provides us with one of the most convincing models of a relationship that links genes with human cognition and behaviour. The hypothesis is that deletion of one or a series of genes causes neurodevelopmental abnormalities that manifest as the fractionation of mental abilities typical of WBS. Detailed molecular characterization of the deletion alongside well-defined cognitive profiling in WBS provides a unique opportunity to investigate the neuromolecular basis of complex cognitive behaviour, and develop integrated approaches to study gene function and genotype-phenotype correlations.

The renal segmental distribution of claudins changes with development

BACKGROUND

Permeability properties of mammalian nephron are tuned during postnatal maturation. The transepithelial electrical resistance (TER) and complexity of tight junctions (TJs) vary along the different tubular segments, suggesting that the molecules constituting this structure change. We studied the differential expression of occludin and several claudins in isolated renal tubules from newborn and adult rabbits.

METHODS

Isolated renal tubules from newborn and adult rabbits were processed for occludin, claudin-1 and claudin-2 immunofluorescence, and Western blot detection of claudin-1 and -2. Claudin-5 was detected in whole kidney frozen sections. RT-PCR from isolated tubules was performed for claudins-1 to -8.

RESULTS

Immunofluorescence revealed that occludin, claudin-1 and -2 were present at the cell boundaries at the neonatal stage of development. Claudin-1 was detected in the tighter segments of the nephron (distal and collecting duct), while claudin-2 was found in the leaky portions (proximal). Claudin 5 was found in the kidney vasculature. PCR amplification revealed the presence of claudins-1 to -4 in tubules of newborns. In adults, claudins-1, -2 and -4 were present in proximal, Henle's loop and collecting segments; claudin-3 was in proximal and collecting tubules, while claudins-5 and -6 were absent from all tubular portions. Claudin-7 was restricted to proximal tubules, while claudin-8 was present in proximal and Henle's segments.

CONCLUSIONS

The pattern of occludin distribution is present from the neonatal age. Claudins-7 and -8 are up-regulated after birth. Each tubular segment expresses a peculiar set of claudins that might be responsible for the permeability properties of their TJs.

Mucosal barrier and immune mediators

The intestinal mucosa functions is an immunologic organ that plays a major role in the development of oral tolerance and host-defense mechanisms. Antigens must cross the intestinal epithelium in a controlled manner to interact with dendritic antigen-presenting cells, because bacteria or their products are a primary risk factor for the development of intestinal inflammation. Therefore, the regulation of the intestinal epithelial cell barrier is central to the development of intestinal immunity and inflammation, but the involved mechanisms are largely unknown. Intestinal barrier function relies on the formation of tight junctions at the apical contact areas of intestinal epithelial cells. Tight junctions have a highly dynamic structure whose permeability, assembly, or disassembly can be regulated by a variety of cellular and metabolic mediators, including cytokines, which have major functions in the immune system. Immune modulators control tight junction dependent intestinal barrier function during development, wound healing, and pathologic processes such as cancer, infection, and chronic inflammation.

Applied genome research in the field of human vaccines

Prophylactic vaccination has made an essential contribution to the improvement of human health over the 20th century. However, we still lack efficient vaccines against major human diseases such as malaria or tuberculosis. Today, the design of therapeutic vaccines referred to as 'pharmaccines' is actively investigated in order to treat diseases such as cancer. In that context, novel ways to rationalize and accelerate vaccine discovery are needed. A series of advances in the fields of molecular biology and computer science, have greatly accelerated the rate at which candidate vaccine antigens can be discovered. In this review, we will present and discuss how applied genome research may facilitate antigen discovery and the design of new prophylactic and therapeutic vaccines.

A complete physical contig and partial transcript map of the Williams syndrome critical region

Williams syndrome (WS) is a contiguous gene syndrome caused by hemizygosity for a chromosomal deletion at 7q11.23. The range of phenotypes includes mental retardation, dysmorphic facies, heart abnormalities, short stature, a specific cognitive profile, hyperacusis, and infantile hypercalcaemia. To identify all the deleted genes, we have constructed a detailed physical map and complete BAC/PAC contig of the critical region, extending a distance of approximately 2 Mb and delimited by the nondeleted markers D7S1816 and D7S489A. Somatic cell hybrids of WS patients were made and used to define the centromeric and telomeric deletion breakpoints, enabling the size of the WS deletion to be defined as approximately 1.4 Mb. Genes previously mapped to the region have been located on the contig, and we have isolated eight transcripts, two of which have been characterized as the genes CPETR1 and CPETR2. This contig and expressed sequence map will form the basis for the construction of a complete transcription map of the deleted region and will enable genotype-phenotype correlations to be attempted to identify the individual components of WS.

SEMP1, a senescence-associated cDNA isolated from human mammary epithelial cells, is a member of an epithelial membrane protein superfamily

We have cloned a human cDNA, SEMP1 (senescence-associated epithelial membrane protein 1), using differential display (DD) of mRNA. We compared mRNA expression profiles between cultured normal senescent human mammary epithelial cells (HMECs) and proliferating, early passage HMECs. From the amino acid sequence of the open reading frame (ORF) of the cDNA, we infer that the protein belongs to a family of membrane-associated, epithelial cell-specific proteins. The translation product has 91% identity to a mouse protein, claudin-1, a tight junction (TJ)-associated protein. SEMP1 mRNA is expressed in human tissues, including adult and fetal liver, pancreas, placenta, adrenals, prostate and ovary but at low or undetectable levels in a number of human breast cancer cell lines. SEMP1 is a member of a superfamily of epithelial membrane proteins (EMPs), which may have multiple potential functions, including maintenance and regulation of cell polarity and permeability, perhaps through mechanisms involving tight junctions.

Claudin multigene family encoding four-transmembrane domain protein components of tight junction strands

Two related integral membrane proteins, claudin-1 and -2, recently were identified as novel components of tight junction (TJ) strands. Here, we report six more claudin-like proteins, indicating the existence of a claudin gene family. Three of these were reported previously as RVP1, Clostridium perfringens enterotoxin receptor, and TMVCF, but their physiological functions were not determined. Through similarity searches followed by PCR, we isolated full length cDNAs of mouse RVP1, Clostridium perfringens enterotoxin receptor, and TMVCF as well as three mouse claudin-like proteins and designated them as claudin-3 to -8, respectively. All of these claudin family members showed similar patterns on hydrophilicity plots, which predicted four transmembrane domains in each molecule. Northern blotting showed that the tissue distribution pattern varied significantly, depending on claudin species. Similarly to claudin-1 and -2, when these claudins were HA-tagged and introduced into cultured Madin-Darby canine kidney cells, all showed a tendency to concentrate at TJs. Immunofluorescence and immunoelectron microscopy with polyclonal antibodies specific for claudin-3, -4, or -8 revealed that these molecules were exclusively concentrated at TJs in the liver and/or kidney. These findings indicated that multiple claudin family members are involved in the formation of TJ strands in various tissues.

Genes for the CPE receptor (CPETR1) and the human homolog of RVP1 (CPETR2) are localized within the Williams-Beuren syndrome deletion

Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder affecting multiple systems. Haploinsufficiency of genes deleted in chromosomal region 7q11.23 is the likely cause for this syndrome. We now report the localization of the genes for the CPE-R (Clostridium perfringens enterotoxin receptor, CPETR1) and the human homolog of RVP1 (rat ventral prostate 1 protein, CPETR2), both previously mapped to 7q11, to the WBS critical region. A single nucleotide polymorphism (SNP) present in CPETR1 has been identified and was used to determine parental origin of the deleted allele in five informative families. The mouse homologs Cpetr1 and Cpetr2 were identified and mapped to the conserved syntenic region on mouse chromosome 5. Northern blot analysis of CPETR1 demonstrates tissue specificity, with expression in kidney, lung, thyroid, and gastrointestinal tissues. In mouse, Cpetr1 is expressed in the early embryo, appears to be developmentally upregulated during gestation, and is present in adult tissues. Our results suggest a role for CPE-R in internal organ development and function during pre- and postnatal life.